The present invention relates to a canister used for an evaporative fuel treatment device of a vehicle, and more particularly to a canister whose DBL (Diurnal Breathing Loss) performance is improved.
As a well-known technique, in order to prevent evaporated fuel (or evaporative fuel) in a fuel tank from being released into the atmosphere, a vehicle using an internal combustion engine is provided with an evaporative fuel treatment device having, as a main body, a canister.
With respect to the canister, an adsorbent such as an activated carbon fills an inside of a casing of the canister. The canister has the function of adsorbing, by the adsorbent, the evaporated fuel generated from the fuel tank in a halt state of the internal combustion engine, and desorbing (purging) a fuel component from the adsorbent and introducing it into an intake system of the engine by the atmospheric air introduced from a drain port at engine start-up or in an engine operating state.
Japanese Unexamined Patent Application No. 2013-249797 (hereinafter is referred to as “JP2013-249797”) and Japanese Unexamined Utility Model Application No. 61-118956 (hereinafter is referred to as “JP61-118956”) disclose a structure of canister in which in order to promote the desorption of the adsorbed fuel component, a heater to heat the adsorbent is provided at the canister using the adsorbent. Especially in JP2013-249797, in order to reduce an amount of the fuel component adsorbed to the adsorbent provided close to the drain port, heating value by the heater is given such gradient that temperature in a position close to the drain port is higher than temperature at purge port side of the canister when applying heat by the heater. As for JP61-118956, it discloses that an activated carbon is heated to 40° C.˜100° C.